Different types of fragrance dispensers are known. Some consist of a piece of material which is impregnated with volatile scent chemicals. However, although such products initially provide high levels of scent delivery, this reduces as the concentration of scent chemicals in the material reduces. Similar disadvantages exist with gel based air fresheners, in which the fragrance material is provided in a gel and evaporates into the air.
In order to overcome such problems, dispensers in which the volatile material is stored in a reservoir and delivered to a dispensing material are known. In particular, so called “plug in” dispensers are available, in which the volatile material is dispensed with the aid of a heated wick to encourage evaporation.
Also, a wick can be used to dispense the fragrance from a reservoir. However, as fragrances generally comprise different “notes”, which evaporate at different rates (“high” notes evaporating more quickly than “bottom” notes), such wicks generally become saturated and clogged with the least volatile “bottom notes” of the fragrance and the carrier material, so that their effectiveness is therefore reduced over time. A fragrance may contain several fragrance components, solvents and residues. The various components provide the character or profile of the fragrance and they have different volatilities ranging from top note (high) to bottom/end notes (low). Historically perfumers have used bottom notes to sustain conventional fragrance products over time because the volatile top notes tend not to last.